The invention relates to a freeze-drying apparatus with a freeze-drying chamber, a condensation chamber and an intermediate support plate which is located between the freeze-drying chamber and the condensation chamber and is equipped with a closeable port.
A freeze-drying apparatus of the, type indicated here is known from the U.S. Pat. No. 3,077,036. The freeze-drying chamber of this apparatus has shelves where the product is placed during the drying process. For achieving the required vacuum and to precipitate the water vapor created during the drying process, a condenser with a valve connection to the evacuation equipment is provided. A check valve is installed between the freeze-drying chamber and the condensation chamber. Check valves are disadvantageous in that they cannot be easily used for flow regulation, i.e. an orifice with a defined cross-section cannot be exactly achieved. Furthermore, an incompletely opened check valve influences the direction of flow of the water vapor between the freeze-drying chamber and condensation chamber such that a one-sided exposure of the condenser results. This entails an unequal loading of the condenser.
The objective of the present invention is to create a freeze-drying apparatus of the type specified above which does not exhibit the described detriments.